changing arduino analog pin for temp sensor

Hi all,

Because my arduino mega analog pin 02 seam to be out of order, I would like to use an other analogic pin assignement for hotend temperature sensor with my RAMP 1.2 and sprinter or Marlin firmware.
(the temp value for hotend are allway 250°, but the bed temp value are ok and i know that the ramp board is ok and the sensor to because i have an other arduino mega for testing it...)

So i will try to use an other free analog pin of the board, maybe the 3, but my question is : how to assign the temp pin in the firmware ??? i think in the pins.h file.....but don't see crearly where....

Any one can help me to find and change this ???


Thank's a lot !!

First off you should troubleshoot a little to make sure what your problem is. for example leaving your heat OFF, switch the connections for the temp sensors. If the beds sensor reads the same 200c (from the hotend readout) when pluged into the hotend temp, then perhaps you are correct something is wrong with that pin.

Another thing, is perhaps your firmware is set to the wrong type of thermistor/thermocouple for your hotend. Do you have the same type of thermistor on your heatbed and your head? If they are different you may need to change your firmware accordingly for your hotend.

If in the end you really have a bad pin or whatever, in Marlin you change your pin assignments in pins.h, (I had to change some to accomodate my reprap discount "smart LCD".) I assume sprinter is similar.

Edited 1 time(s). Last edit at 01/01/2013 01:57PM by xclusive585.

Hi Xclusive585,

thank's for your answer.
Yes i'have tested to swap the connection with the bed (it have the same type of thermistor to...) and the pin display only this value 250°. And it allway the same thing when any sensor is connected... I have tested my RAMP 1.2 with other arduino board and all is ok, the sensor display the good value. I don't have changed the type of thermistor in the firmware, and as it whas ok beffor...i'm sure for now that's the pin is out of order.

I have find the variable in the Marlin pins.h file (i don't see before the special configuration for Ramp 1.2 and lookin in the 1.3 section...), to swap the value with the bed pin, and now it's ok and the Temp is read from the sensor..!!